I have spent my entire life at the borders of continental Europe. From the window of my home or office, I've looked out over the Bosphorus to see Asia on the other side; and so, in thinking about Europe and modernity, I have always felt, like the rest of the world, just a little bit provincial.

Like the many millions who live outside the west, I have had to understand my own identity while observing Europe from afar, and so, in the process of working out my identity, I've often wondered what Europe could represent for me and for us all. This is an experience I share with the majority of the world's population, but because Istanbul, my city, is situated just where Europe begins – or maybe where Europe ends – my thoughts and my resentments have been a little more pressing and constant.

I come from one of the many upper-middle-class Istanbul families who wholeheartedly embraced the westernising, secularising reforms introduced in the 1920s and 30s by Kemal Atatürk, founder of the Turkish republic. For us, Europe was more than somewhere we could go to find a job, a place to trade with, or whose investors we could seek to attract: it was primarily a beacon of civilisation.

At this point I should highlight an important fact: historically, Turkey was never colonised by any western power, never oppressed by European imperialism. This allowed us later to nurture more freely our dreams of European-style westernisation, without dredging up too many bad memories or guilty feelings.

Seven years ago I used to try to persuade audiences how wonderful it would be for us all if Turkey were to join the EU. Back in October 2005, relations between Turkey and the EU had reached their peak. Turkish public opinion and most of the press seemed happy that talks between the EU and Turkey had officially begun. Some Turkish newspapers speculated optimistically that things might move very quickly indeed, that Turkey might enjoy full membership of the EU by 2014. Other papers wrote fairytale accounts of the privileges Turkish citizens would finally gain once full membership was secured. Most importantly, investments would be made and untold treasures would find their way to Turkey from the EU's various funds so that, like the Greeks, we too would collectively take a step up the social ladder and be able to live as comfortably as other Europeans.

At the same time, the European chorus of conservative, nationalist protest against Turkey's possible entry into the union was growing increasingly vocal, especially in Germany and France. I found myself caught in this debate, and began to ask myself (and others too) about what Europe really means. If religion marks the boundaries of Europe, I thought, then Europe is a Christian civilisation – in which case Turkey, whose population is 99% Muslim, may be geographically European, but has no place in the EU.

But would Europeans be satisfied with such a narrow definition of their continent? After all, it is not Christianity that has turned Europe into an example for people living in the non-western world, but rather a series of social and economic transformations, and the ideas that these have generated throughout the years. This intangible force that has made Europe such a magnet for the rest of the world over the past two centuries is, to put it simply, modernity. As our trusted history books have taught us, modernity is the product of such quintessentially European developments as the Renaissance, the Enlightenment, the French Revolution and the Industrial Revolution. Crucially, the forces behind these paradigm shifts were not religious, but secular.

A few years ago, whenever the topic of the EU came up for discussion, I used to say that Turkey should join the EU provided it could respect the principles of liberty, equality and fraternity. "But does Turkey respect these principles?" people would rightly ask me – and so the debate would resume. When I look back at those days now, I can't help feeling nostalgic about how passionately we debated – both in Turkey and in Europe – the values that Europe should stand for.

Nowadays, as Europe struggles with the euro crisis, and EU expansion has slowed down, very few of us still bother to think and talk about these issues. And unfortunately, the positive interest surrounding Turkey's possible future membership has also waned. This is partly because freedom of thought remains regrettably underdeveloped in Turkey. But the biggest reason is undoubtedly the large influx of Muslim migrants from north Africa and Asia into Europe that, in the eyes of many Europeans, has cast a dark shadow of doubt and fear over the idea of a predominantly Muslim country joining the union.

It is clear that this fear is leading Europe to put up walls at its borders, and to gradually turn away from the world. As the slogan of liberté, égalité, fraternité is slowly forgotten, Europe will sadly turn into an increasingly conservative place dominated by religious and ethnic identities.